Brian Cox - What Was There Before The Big Bang?

[Music] it's interesting this idea of the Big Bang  created the universe that's what Einstein's theory   says that's textbook cosmology if you like but the  current textbook picture is there was a phase in   the universe's life before the Big Bang if you  define the Big Bang as the hot dense phase from   which the universe appeared to sort of burst  for 13.8 billion years ago and that phase is   called inflation so what we think happened is  that before that the Universe was accelerating   exponentially fast it means it was doubling and  doubling and doubling in size and the numbers   are ridiculous we think that if you started with  the universe that was smaller than a single atom   then it would be bigger by a long way than the  whole observable universe 350 billion galaxies   in it in less than a million million million  million million millionths of a second so   a very rapid exponentially fast expansion and when  that stopped all the energy that was driving that   expansion got dumped into space it heated  it up it produced the particles of matter   out of which we are made and all the things  that we see out there in the sky and that's   what we see as the Big Bang so that sounds  fanciful but that's standard cosmology at   the moment the big question then is well what  started the inflation what stops the inflation   how long did the inflation go on for and the  answer to that is we're not sure we don't know   in the beginning there was an infinitely dense  tiny ball of matter which started to expand and   would eventually give rise to the atoms molecules  stars and galaxies we see today but what was there   before the Big Bang what was the state of the  universe before well everything the universe   underwent a breathtaking Cosmic expansion doubling  in size at least 80 times in the fraction of a   second this rapid inflation fueled by a mysterious  form of energy the permeated empty space itself   left the universe desolate and cold and only after  that did the hot dense conditions of the Big Bang   emerge some of those theories suggest that the  inflation doesn't stop all at once it stops in   patches and every time it stops you get a universe  and so some of these Theory they're called   Eternal inflation theories suggest that there  might not be just our universe the bit that we   can see but there might be many universes perhaps  an infinite number of them and they may be being   produced all the time so what to make of that  but that's where her current modern cosmology is   if Cosmic inflation correctly describes what  happened before the Big Bang it may push the   ultimate answer to the question of where we came  from beyond the reach of science but that just   pushes the question further because we don't know  anything about what came before inflation and it's   doubtful that we'll ever know there are theories  now that suggest as I mentioned that there may   be more than one universe and potentially an  infinite number it's a mind-boggling idea isn't   it now I should say one extra thing if that's  true then some of those theories say that what   we call the constants of nature so things like  the strength of gravity the speed of light the   masses of the particles can vary from University  universe and then you ask the question well why is   our universe so perfect for life why do stars make  carbon and oxygen the elements that you need for   life why is everything so beautifully balanced  so that living things can exist the answer in   these cases is because well every Universe exists  every possible combination of the laws of nature   exist if different universes so the reason we  obviously the reason we we have to see a Universe   that allows us to exist obviously we could ask  the question well How likely is that well the   answer there are an infinite number of them is  it's inevitable because there's every possible   kind of Universe And I stress that this is very  speculative stuff but the first thing I said about   inflation the idea there's this exponentially  fast expansion before the Big Bang if you want   to use that language that's not speculative that's  mainstream cosmology but this idea that that may   lead to multiple universes is more speculative  but it's still scientifically valid and there are   people who do research into that and again this  is an active area of research inflation tells us   that the period of time before the Big Bang was  extremely cold and it was empty of everything but   empty space and that empty space carried energy  that stretched the universe out to this enormous   size and into the initial State before the Big  Bang but there are also alternate theories to   cosmological inflation which tell us what caused  the initial conditions that would eventually give   rise to the Big Bang there's a theory there may  be extra dimensions in the universe so imagine   that we we're just living on a sheet of paper  let's say then there are theories where here's   our universe floating around and there can be  another Universe floating around so there are   more spatial dimensions and we're just on a sheet  floating around in this bigger Multiverse and then   you can ask the question what happens when they  collide together and one of the theories about   what caused the Big Bang is that actually what it  was was two of these sheets or branes they called   so they collide together and separate and when  they collide together they heat themselves up   and you get something that looks like a big  bang on that sheet of space and time if you   like so that's another different theory for what  happened before the Big Bang branes colliding into   each other giving rise to Big Bangs Multiverse  theories these statements might seem extremely   speculative and out of touch with reality but they do  in fact have mathematical reasoning behind them   and moreover theories describing the very early  state of the universe do have experimental support   the wonderful thing is that we can we're making  measurements now I should say the experimental   basis for all this is something called The Cosmic  microwave background radiation of the CMB so we   can look up into the sky and we can see the oldest  light in the universe it was released at 380 000   years after the big bang it's when the universe  cooled down sufficiently for atoms to form and   at that point the universe became transparent  and that light has been traveling through the   universe ever since and we have a satellite up  at the moment called Planck so European satellite   that's been taking detailed pictures of this light  and in that light it's like a baby picture of the   universe like a scam a baby scan of the universe  in a sense and so you can look to the universe   as it was in its very earliest days and see  different structures and different properties of   that light and they give you the clue as to what  happened right back at the beginning of time the   beginning of the universe and that's where these  theories are getting their experimental support   the twin pillars of modern physics are Einstein  Stein's general relativity and quantum theory   to understand how the big bang emerged and  what came before it it is essential to unite   Einstein's theory with quantum theory only if we  obtain such a theory will we be able to answer   the ultimate questions in cosmology like what is  space what is time what is the universe and where   did it come from the most distant objects in the  universe are 47 billion light years away making   the size of the observable universe 94 billion  light years across if you are wondering how can   the observable universe be larger than the time it  takes light to travel over the age of the universe   the answer is because the universe has been  expanding during this time and this causes very   distant objects to be further away from us than  their light travel time most scientists think the   entirety of the universe extends Way Beyond the  observable universe but is there anything beyond   the entirety of the universe is there anything  beyond the universe probably not we suspect quite   strongly that our universe could well be infinite  in extent even now a bit of the universe if you   just take our universe it certainly we're sure it  exists far beyond the bit we can see so why would   I say that well if you think about it the universe  is that our bit at least has been around for 13.8   billion years that means that light has only had  13.8 billion years to travel from the bit that we   can see to our eye so we can only see as far as  light as had time to travel but we think there's   a lot beyond that because of measurements we've  made of how the universe is curved and what the   structure of the universe is so it undoubtedly  extends beyond the little bubble that we can see   how far it extends it's another great question  we don't know but it could be infinite an extent   taking into consideration the latest discoveries  and measurements in physics we have attempted to   answer the questions what was there before the  Big Bang how big is our observable universe and   what lies beyond the bit we can see but are we  forgetting something an important question that   naturally arrives after we question the beginning  of everything how will the universe end well the   current best guess or best estimate is that it  will carry on expanding forever and the reason   I say that is because actually the universe is  accelerating in its expansion which is a great   mystery because before that Discovery we thought  well gravity is always attractive and so it should   be we've got all these galaxies in the universe  and the universe has been expanding since the big   bang and so it should at least be slowing down and  there's even a question as is there enough matter   in it to slow it down so much that it stops and  recollapses again but this new discovery that the   universe is accelerating in its expansion suggests  that it will continue to to accelerate unless some   new physics appears that we don't understand  and so it will just continue to expand forever thanks for watching did you like this video  then show your support by subscribing ringing   the bell and enabling notifications  to never miss videos like this [Music]

Channel: Science Time

Views: 1,000,240

Keywords: brian cox, brian cox before the big bang, brian cox big bang, before the big bang, what happened before the big bang, brian cox inflation, cosmological inflation, space, brian cox cosmos, is the big bang wrong, brian cox multiverse, brian cox brane multiverse, brian cox quantum physics, physics, spacetime, einstein, time, the universe, big bang cosmology, is the universe infinite, how big is the universe, science time

Id: BD0r2Xfgh_E

Length: 10min 11sec (611 seconds)

Published: Sat Jan 07 2023

Reddit Comments

[u/space_monster]

if time is a property of the physical universe, there doesn't have to be anything before inflation, because the concept of 'before' didn't exist before inflation. causality is meaningless. there is only a start and end if you're in the universe. outside of that, the only valid question is "does the universe exist?" and the answer is "yes".